Vibratory switching mechanism



July 8, 1969 A. NYFELER 3,454,910

VIBRATORY SWITCHING MECHANISM Filed Jan. 9, 1967 INVENTOR.

BY fi/ex A/y/e/er WW Fvuuzaw P l u.

United States Patent 4 Int. Cl. Htllh 51/34; H02k 33/02, 35/00 US. Cl. 335-94 14 Claims ABSTRACT OF THE DISCLOSURE A vibratory switch mechanism utilizing a tuned blade clamped at one end and having a mass of ferromagnetic material at the other end of said blade, with means to shorten the part of the period of oscillation of said blade in which the electrical contacts are open.

The invention relates to an electromechanical contact device with a switching contact for periodically closing and opening an electric circuit. The member actuating the contact is a blade of resilient material which is induced to oscillate by a magnetic alternating field. Related subject matter is found in applicants copending application Ser. No. 607,987 filed concurrently and entitled, Oscillating Circuit With Vibratory Switch.

Contact devices of this type are known in numerous forms and are used in resonance relays, transformers, inductors, etc. and with known means for generating audio frequency pulses. The latter have as the audio frequency source an electrical oscillatory circuit which is periodically connected to a voltage source by a contact device including an oscillating blade. The voltage source may be an AC energy distributing network which serves to transmit the generated audio frequency pulses.'. The latter, after being decoupled at a different point in the network, are evaluated as signals. The information elements in such signals may be, for example, the frequency of the electric oscillatory circuit, the switching frequency of the contact device, a pulse (code) or a combination of these.

The contact device with an oscillating blade for periodically connecting an oscillatory circuit to an AC energy distributing network for the purpose of producing signals must operate very accurately and substantially without chattering. If audio frequency pulses with the highest possible energy are to be obtained it is further desirable for the switching contact to be closed longer than it is open within an oscillating period of the blade, and for the contact to be closed and opened at different transient values of the main AC voltage, preferably near to peak values of opposite polarity. These requirements cannot be adequately fulfilled by known mechanical contact devices. It is accordingly an object of the invention to provide a contacting device which despite its very simple construction, has all the required properties.

A contact device of the type herein described comprises an oscillating blade which is clamped on one side and which carries at its distal end an oscillating mass of the ferromagnetic material arranged within the field of an electromagnet. The device further includes, near the clamping point, a contact element arranged opposite a contact member which is rigidly connected to a holder for the blade. According to the invention, this arrangement further includes a blade spring clamped into the holder and arranged within the oscillating range of the blade, the blade being tuned to a given self-oscillation rate; for at least a part of a full oscillating period of the blade, the spring is applied to the blade outside the portion of the 3,454,910 Patented July 8, 1969 latter lying between the clamping point and the contact element.

Examples of the apparatus according to the invention are described in greater detail hereinafter with reference to the drawings, of which:

FIGS. 1 and 2 are schematic diagrams of two contact devices according to the invention, and

FIG. 3 is a schematic diagram of a circuit utilizing an illustrative contact device.

In FIG. 1, 1 refers to an oscillating blade which is clamped into a holder 3 at a point 2, the end 4 opposite the point 2 being provided with an oscillating mass 5 of ferromagnetic material. Near the clamping point 2 the blade 1 carries a contact element 6 arranged opposite a contact member 8 which is fixed to a yoke 7 rigidly connected to the holder 3. The element 6 and member 8 together form a feeler contact 9. A portion 10 of the blade 1 projecting beyond the clamping point 3 acts as a current supply to the contact element 6 of the blade 1.

Within the oscillating region, preferably in the oscillating plane of the blade 1, which should be thought of as lying parallel with the plane of a drawing, the blade spring 11 is fixed to the holder 3 parallel with the blade 1; its'free end portion 13, which points towards an electromagnet 12, is in contact with the oscillating mass 5 at an engaging surface 13 thereon which is preferably near the center of gravity of the mass. The spring 11 should desirably be suitably rounded at the surface 13. The rigid connection between the spring 11 and the holder 3 is established, for example, by a clamping member 14. The blade 1 and spring 11 can advantageously be clamped into the holder in such a way that they touch each other gently at the resting place 13 when the two springs are relaxed. The contact element 6 is then at a defined spacing-as small as possiblefrom the contact member 8, the spacing being a few tenths of a millimeter, e.g. 0.2 to 0.3 mm. In special cases the oscillating mass 5 can be dispensed with; the spring 11 would then be in direct contact with the blade 1.

The portion of blade 1 between the element 6- and the clamping point 3 has a slight bias so that part of the element 6 is applied to a stop 15 on the holder 3 when the contact device is in certain positions of use, selected as desired. An asymmetrically offset arrangement of the electromagnet 12 in relation to the mass 5, as shown in FIG. 1, insures that the blade 1 will start its oscillating movement in a favorable manner. Adjusting means such as set screws may of course be provided so that the spacing between the two members of the feeler contact 9 can be adapted as required. But as a general rule the adjustment is determined by the manufacturing tolerances and can in any case be corrected by bending the yoke 7 with the aid of a pair of adjusting pliers.

As noted he-reinbefore, the time during which the feeler contact 9 is closed must be longer than the time that it is open. This, however, is incompatible with the abovementioned indispensable measure, that the oscillating blade 1 be applied with a slight bias to the stop 15 on the holder 3, for example over part of the contact element 6. In this construction of the contact de-vice this difiiculty is overcome, in that the oscillating time of the oscillating system is shortened, by the action of the spring 11 on the mass 5, during the half oscillation when the feeler contact 9 is open.

The oscillating time of the oscillating system of the contact device is made up in this arrangement of two parts; starting from the neutral position shown in FIG. 1, there is a half period during which the blade spring 11 is active, then a short interval of the second half period during which interval the mass 5 cover a distance corresponding to the contact spacing. During this interval, the full length of the blade 1, i.e. the spring length from the mass to the clamping point 2, is effective. Finally, there is the remaining part of the second half period, during which time the blade 1 virtually oscillates freely in a downward direction as shown in FIG. 1 with the contact 9 as its clamping point.

The self-oscillation rate of the oscillating system is determined by the reciprocal value of the combined oscillating time. By suitably selecting the spring constants of the blade 1 and spring 11, and by appropriately dimensioning the mass 5 and arranging the feeler contact 9, the oscillating time for a first half period may, for example, be set at milliseconds (corresponding to 50 cycles per second) and the oscillating time for the succeeding, second half period at 30 milliseconds (corresponding to- 16 /3 cycles per second). Hence, the total oscillating time for a full period of oscillation of the system will amount to 40 milliseconds, corresponding to a self-oscillating rate of 25 cycles per second. This frequency of 25 cycles per second can be produced by energizing the electromagnet 12 with a main alternating current of 50 cycles per second. Various other operating frequencies of the oscillating system are of course possible, for example such that the self-oscillating rate forms a harmonic of the frequency of the alternating current energizing the electromagnet 12. The frequency of the current energizing the magnet is, however, preferably a harmonic of the frequency of the blade 1, i.e. of the oscillating system including the blade 1. At a given frequency of the energizing current, tuning to certain low self-oscillation rates can easily be achieved if the oscillating mass 5- is permanently magnetically polarized. In such a case, it would be in the form of a permanent magnet.

Since the distance between the two elements of feeler contact 9 is very small, the contact is in the closed state (into which it passes almost without chattering because of its low speed) for approximately 30 milliseconds, i.e. of the total oscillating time. The electromagnet 12 is preferably arranged so that it displaces the oscillating system to the side with the shorter oscillating time. The energizing frequency and resonance frequency in this half wave are, for example, equal, thus giving very good starting properties. For this reason the electromagnet 12 is shown in FIG. 1 as being offset in the direction of the spring 11. The friction at the site 13 where the spring 11 rests on the mass 5 produces a weak damping action, ensuring that the oscillating system will vibrate rapidly in and out.

A somewhat simplified embodiment of the contact device is illustrated in FIG. 2, in which parts that are the same as in FIG. I bear the same references. In this arrangement the functions of the stop 15 described in FIG. 1 are combined with those of the blade spring 11.

In the FIG. 2 arrangement a yoke spring 16 serves to shorten the half period of the oscillation time of the system corresponding to the open state of the contact 9; the spring 16 has a relatively high spring constant as compared with that of the blade 1 and is fixed to the holder 3. The action of the yoke spring 16 is based chiefly on the shortening of the free length of the oscillating system for the duration of a half period. In this way the action achieved is of the same quality as that described in connection with FIG. 1.

FIG. 3 illustrates the aforementioned use of the contact device. It again shows the contact device including the oscillating blade 1, feeler contact 9 and electromagnet 12. The feeler contact 9 is electrically connected, in series with an electrical oscillatory circuit 19 comprising a capacitor 17 and a coil 18, to a source of AC voltage, e.g. an AC voltage network with a mains frequency of 50 cycles per second. The electromagnet 12 is connected to the same source by way of a switch 20. A resistance capacitor combination is generally connected in parallel with the feeler contact 9 in order to extinguish arcs.

When the switch 20 is closed the blade 1 begins to oscillate and. as alreadv mentioned bv wav of example.

the feeler contact 9 is closed for 30 milliseconds per oscillating period of the contact device. If, by means of suitable tuning, the closing of the contact is continuously timed to coincide with a point in the main period, e.g. with a positive voltage maximum of the 50 cycles per second main AC voltage, then the contact will open just at the maximum negative transient value of the main AC voltage. If, as mentioned in the example, the oscillating time of'the oscillating system of the contact device amounts in total of 40 milliseconds, the feeler contact 9 will close again within the positive main voltage maximum. Each time the contact 9 is closed the electrical oscillatory circuit 19 is induced to carry out suppressed audio frequency oscillations, their initial amplitude being proportional to the sum of the transient value of the main AC voltage at the time when the contact 9 is closed and the residual voltage then present at the capacitor 17. The initial amplitude can reach its possible maximum only if the contact 9 is closed at a peak value of the main AC voltage and if the capacitor 17 is simultaneously charged at least approximately to said peak value with opposite polarity. This situation obtains when the time during which the contact 9 is closed is equal to the single value or to an odd multiple of the duration of half a period of main AC voltage, as is the case of the contact device described. The closing of the contact 9 can be timed to coincide with the maximum value of the main AC voltage if mechanical, and in any case electrical tuning, is carried out by a phase advancer.

The entire complex of the AC network suppresses the oscillatory circuit 19 to a small degree, so that its audio frequency vibrations die down only comparatively slowly. As a result of the long connection time that can be obtained with the contact device described and in view of the favorable duty cycle, i.e. the ratio of the time when the contact '9 is closed to the time the contact is open, the greater part of the energy of the audio frequency vibrations can be put to use as signalling energy. In this way, the contact device described solves a problem which could hitherto be overcome only with substantially more complex, motor-driven cam-type feeler contacts.

In the study and practice of the invention, modifications will undoubtedly occur to those skilled in the art; the invention is thus not limited to the specific mechanisms and processes herein shown but departures may be made therefrom within the scope of the accompanying claims Without departing from the principles of the invention and without sacrificing its chief advantages.

What is claimed is:

1. A vibratory switching mechanism comprising a holder, an oscillating blade tuned to a predetermined frequency and clamped at one end in said holder, an oscillating mass of ferromagnetic material at the distal end of the oscillating blade, an electrical contact element carried by said oscillating blade adjacent said clamped end, an electrical contact member rigidly connected to said holder and disposed opposite said electrical contact element carried by the oscillating blade, means for energizing said oscillating mass, and a blade spring clamped at one end in said holder and arranged in the plane of oscillation of the oscillating blade to contact said oscillating blade on the side of the contact element remote from the clamped end during at least a part of the oscillating period when the electrical contacts are open to shorten the part of the period of oscillation of said oscillating blade in which the said electrical contacts are open- 2. A vibratory switching mechanism as in claim 1 including the further improvements of a protuberance located on the oscillating blade on the side opposite from the electrical contact at the point at which said electrical contact is located and a rigid stop member in alignment with said oscillating blade on the side thereof remote from said electrical contact whereby the stop engages the protuberance to shorten the period of oscillation of said oscillating blade during the part of the period in which the electrical contacts are open.

3. A vibratory switching mechanism as in claim 1 wherein the spring has a spring constant which is relatively large compared with the spring constant of the oscillating blade.

4. Switching means according to claim 1 wherein said spring is in contact with said oscillating mass substantially at the center of gravity of said mass.

5. Switching means according to claim 1, wherein that portion of said spring which is in contact with said blade has rounded edges.

6. Switching means according to claim 1, wherein said blade and spring are clamped in said holder in a configuration such that in the relaxed state they lightly touch one another and said contact element is spaced less than 0.3 millimeter from said contact member.

7. Switching means according to claim 1, wherein the means for energizing the mass of ferromagnetic material is an electromagnet and the longitudinal axis of said blade, when relaxed, is offset from said electromagnet in the direction of oscillation.

8. Switching means according to claim 7 including a source of AC current for energizing said electromagnet and having a frequency equal to a harmonic of the selfoscillation rate of said blade.

9. Switching means according to claim 1, wherein said spring and blade have spring constants such that the frequency of the blade alone is about 16% cycles per second and the frequency of the blade when energized by said spring is about 50 cycles per second.

10. Switching means according to claim 3, wherein said spring and blade have spring constants such that the frequency of the blade alone is about 16 /3 cycles per second and the frequency of the blade when energized by said spring is about cycles per second.

11. Switching means according to claim 7, wherein said electromagnet is offset towards said spring.

112. Switching means according to claim 1, wherein said blade is magnetically permanently polarized.

13. Switching means according to claim 1, including alternating means for energizing said mass and wherein said blade has a self-oscillation rate which is a harmonic of the frequency of said alternating means.

14. Switching means according to claim 1, including an electric oscillatory circuit and an AC voltage network, said switching means being connected to said circuit and said network for periodically connecting same.

References Cited UNITED STATES PATENTS 2,073,913 3/1937 Wigan 335-87 2,606,259 8/ 1952 Huetten. 2,906,837 9/1959 Gimson 33590 2,972,070 2/1961 Loverde 3 l025 BERNARD A. GILHEANY, Primary Examiner. H. BROOME, Assistant Examiner.

US. 'Cl. X.R. 200-1 66; 310-25 

